Ampex 620 Owners Manual

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Copyright l954 by Ampex Corporation

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AX OPERATOR'S GUIDE

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Your Ampex Model 620 Amplifier-Speaker repre-
sents a maior advance in the quality ot sound
reproduction available in a small portable unit.
The sound output of the speaker is tested acous-
tically in production and is flat and tree from
appreciable dips and rises in response over the
frequency range of 65 to l0,000 cycles per second.
You will hear remarkable bass, and an excellent
balance in midrange and high frequencies. To
achieve this superb performance, the amplifier,
speaker and enclosure were specially made for
each other, The Ampex 620 is a completely inte-
grated design rather than a collection of inde-
pendently designed units.

The perfect signal source for the Ampex 620 is the
Ampex Model 600 portable tape recorder which
it matches in performance and appearance. The
Model 620 will also provide excellent reproduc-
tion when used with record changers, turntables,
AM-FM or TV tuners, or microphone preamplifiers.
This guide should enable you to utilize its versa-
tility, power, and range with any of these sources.

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(I) POWER SWITCH

lH) IJNE FUSE

(G) EXTERNAL
SPEAKER JACK

(F) EQUALIZATION
(E) PILOT LIGHT coNTROL

(oi LEVEL CONTROL

(A) AC.
CONVENIENCE OUTLET

(B) INPUT CONNECTOR

IC) A.C.
POWER RECEPTACLE

The operation of the Ampex 620 requires only a simple understanding of
the controls and the input and output connections.

POW E R

1. The power cable furnished should be connected from the POWER re-
ceptacle (C) to any source of nominal II7-Volt 50 or 60 cycle AC power.

2. The second AC connector (A) is a convenience outlet which may be used
to furnish power to auxiliary equipment.

3. The 620 is turned on and off with the POWER switch (I). This switch
does not control power at the convenience outlet. The pilot light
(E) indicates that the 620 is ON.

4. The line fuse (H) on the 620 is a I Ampere SAG type.

IN P U T

1. The INPUT connector (B) takes a standard phono pin plug. Most phono-
graphs and tuners are equipped with this type of connector and may
be plugged directly into the 620. A shielded interconnecting cable is
furnished primarily for use with the Ampex Model 600 tape recorder.
Any cable used to connect the 620 to other equipment should be of the
shielded type.

2. The Model 620 has a 20,000-ohm input impedance and may be fed from
any equipment for which this or a lower output impedance is specified.

O U T PU T

'I. The internal speaker of the Model 620 is used in normal operation. An
external speaker may, however, be plugged into the EXTERNAL SPEAKER
jack (G). Insertion of an external speaker plug automatically disconnects
the internal speaker.

2. The amplifier in the Model 620 has a low output impedance and will
operate satisfactorily into external speaker load impedances of approxi-
mately I2 ohms.

CONTROLS

'l. The two controls on the Model 620 are the LEVEL or volume control (D),
and the EQUALIZATION or tone control (F).

2. The EQUALIZATION control will increase bass and decrease treble
when turned to the left, or decrease bass and increase treble when turn-
ed to the right. The center position provides flat response. This control
may be used to improve the overall result under poor acoustical condi-
tions, or simply to satisfy the listener's ear.

Your Model 620 is a versatile unit, readily adaptable to a variety of prac»
tical applications. It can be used as a portable public address system, a
guitar amplifier, or a remote auxiliary unit for a fixed sound installation.
See your distributor for advice on these special applications.

The use of the Model 620 in coniunction with the Ampex Model 600 Re-
corder as a portable public address system is covered in detail below as
an example of what can be done with this unit.

Models 620 and 600 as a Portable PA System

. Connect a microphone to the Model 600.

. Connect the Model 600 output to the Model 620 input.

. Turn the Model 600 MONITOR SELECTOR to the INPUT position.

. Turn both machines on.

. Set the Model 600 MIC REC LEVEL control exactly as for making a
recording.

. Adiust the loudspeaker volume with the LEVEL control on the Model 620.
(The MIC REC LEVEL control on the Model 600 will also affect loud-
speaker volume, but it should not be used for this purpose once it has
been set as in Step 5.)

7. A recording of the program may be made simultaneously by simply
threading a tape on the Model 600 and placing the machine in the
record mode. This will not affect the public address operation.

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